A Heart Rate Measurement System Based on Ballistocardiogram for Smart Furniture

This paper presents a novel on-chair heart rate detection system based on ballistocardiogram (BCG) using sensor cores placed symmetrically on steel plate. The sensor cores are designed based on piezoelectric effect to detect weak vibrations from body. A 3-stage circuit is designed with cutoff frequency of 0.1-10Hz and a gain of 10 to interface with piezoelectric sensor core. The symmetrically placed sensors produce signals in opposite direction that cancel the motion artifacts when the body swings from left-to-right or vice versus. Measurement results show that the proposed system enhances the signal-to-noise ratio (SNR) by around 2 times. The experimental results also demonstrated that the proposed system detects high-quality BCG signals when small body movement is induced during measurement.